Biosecurity and minimal disease herds.

The minimal disease concept is a way of raising pigs so that some specific diseases are absent. Many bacteria and viruses can be transferred by pigs, air, or mechanical contact. To avoid contamination, the herd location should take into consideration disease transmission possibilities. Herd health status and source herd health status should be continuously monitored. To maintain herd health status, specific rules need to be followed for herd construction and establishment, compound perimeter, people movement, down time, animal transportation, feed use and delivery, vehicle movement, material, dead animal disposition, and rodent control. All new incoming animals should go through quarantine, and in some herds, safer methods such as AI, embryo transfer, MEW, or hysterectomy and fostering need to be used.     

Development of a microcomputer system for recording veterinary visits, preparing accounts, and as an aid to herd fertility and herd health schemes

A computerised method of recording clinical information from farm animal practice visits and using it for herd fertility visits, herd health schemes, the investigation of disease outbreaks and as a source of data for epidemiological studies was developed in the University of Liverpool farm animal practice. The system stores clinical and reproductive information in a data base from which data can be readily extracted and analysed, and monthly bills produced.     

A case-control study on the association of selected risk factors with the occurrence of bovine tuberculosis in the Republic of Ireland

We did a case-control study on the association between the occurrence of bovine tuberculosis in herds in the East Offaly area and a number of possible risk factors: herd size, the purchasing of cattle, the herd history, the status of contiguous herds, distance to the nearest badger sett, and animal factors such as age, breed and animal type. The characteristics of 100 herds that had a confirmed outbreak of tuberculosis at a herd test in 1988 were compared with those from an equal number of herds that passed at least one tuberculin test during that year. The study base consisted of 1379 herds mainly from the eastern part of County Offaly. The data were analysed at both herd and animal levels. Factors that were associated with an increased risk of tuberculosis breakdowns at the herd level were (i) the total number of animals in the herd and (ii) the restriction of a contiguous herd for tuberculosis within a period of 6 months prior to or following the herd under study. A number of factors were associated with an animal having an increased risk of failing a tuberculin test. After adjusting for all other variables in the model, cows, heifers and bullocks were 10.3, 14.8 and 8.0 times, respectively, more likely to fail a tuberculin test than calves. Cattle that had teen purchased since the previous herd test were less likely to fail a tuberculin test compared with cattle that had been present at the time of the preceding herd test.     

Culling practices of Ontario cow-calf producers.

This study describes the distribution of herd culling rates for 123 Ontario cow-calf herds maintaining individual animal records. Associations between culling and factors at both the individual and herd level were examined. In addition, the relative importance of individual animal and herd level influences on culling were investigated. The following individual cow culling risk factors: nonpregnancy, age, weaning weight index, calf outcome, abortion, prolapsed vagina, prolapsed uterus, calving injury, lameness and mastitis or udder problems were significantly associated with culling (p less than 0.01). Two herd level factors were associated with increased culling rates: a higher than average proportion of heifers and a shorter than average calving season (p less than 0.01). The proportion of culling variation attributed to individual animal and herd level influences varied with model type. While simple models (one-way ANOVA) indicated that the herd variance component for culling was relatively minor, more complex models indicated larger herd-to-herd variability (mixed model ANOVA). Thus, it appeared that the probability of culling for a cow with a given set of risk factors depended to an important extent on manager decisions in the herd of origin.     

基于Excel的个体近交系数直观估算

通过计算畜群内的个体近交系数,可以把握现有畜群的遗传效应,对于畜群的选种选配有着重要的指导意义,能有效地防止近交造成的品种退化等现象。通过Excel函数计算畜群系谱信息中共同祖先出现的次数频率,可简单快速地估算个体间的近交系数,实现近交系数的直观估算,不需要使用者掌握计算机编程知识,可供基层畜牧行业的技术人员参考使用,能快速估算系谱个体的近交情况,使得对群体遗传效应的评估工作极易进行。     

Database system for herd health management of dairy herds especially for udder health

Integrated herd health management is an effective method to improve animal health as mastitis and fertility disorders in dairy herds. For optimizing the costs and work load for the herd health management, it is necessary to have a data tool that enables a quick and comfortable data handling and provides practicable handouts for extension. The Research Institute of Organic Agriculture in Switzerland (FiBL) has developed such a database-system for the animal health management project "pro-Q". Objective of this database is to combine external available and on-farm collected data and to provide routine tools on herd and cow level (incl. udder quarter level) for farmers, veterinarians and advisers. These tools should give a comprehensive overview over the animal health situation of the herd and the single animal level. Furthermore, the database presented in this article, meets the requirements of a multi-user system with remote-access which enables different instances to gain the requested information.     

Potential infection-control benefit for Ireland from pre-movement testing of cattle for tuberculosis

Pre-movement testing for bovine tuberculosis (BTB) was compulsory in Ireland until 1996. We determined the proportion of herd restrictions (losing BTB-free status) attributable to the recent introduction of an infected bovid; described events between restoration of BTB-free status (de-restriction) and the next herd-level test for BTB; estimated the proportion of undetected infected cattle present at de-restriction; identified high-risk movements between herds (movements most likely to involve infected cattle); and determined the potential yield of infected cattle discovered (or herds that would not lose their BTB-free status) by pre-movement testing, relative to the numbers of cattle and herds tested. We used national data for all 6252 herds with a new BTB restriction in the 12 months from 1 April 2003 and 3947 herds declared BTB-free in the 12 months from 1 October 2001. We identified higher-risk animals from our logistic generalized estimating-equation models. We attributed 6-7% of current herd restrictions to the recent introduction of an infected animal. There were considerable changes to herd structure between de-restriction and the next full-herd test, and infection was detected in 10% of herds at the first assessment (full-herd test or abattoir surveillance) following de-restriction. Following movement from a de-restricted herd, the odds of an animal being positive at the next test increased with increasing time in the source herd prior to movement, increasing time between de-restriction and the next full-herd test and increasing severity of the source herd restriction. The odds decreased with increasing size of the source herd. We estimated that 15.9 destination-herd restrictions per year could be prevented for every 10,000 cattle tested pre-movement and that 3.3 destination-herd restrictions per year could be prevented for every 100 source herds tested pre-movement. The yield per pre-movement test can be increased by focusing on high-risk movements; however, this would result in a substantial decrease in the total number of potential restrictions identified.     

Neospora caninum seroprevalence in dairy and beef cattle from the northwest region of Spain, Galicia

Herd and individual animal seroprevalence for Neospora caninum (N. caninum) in dairy, beef and mixed cattle were obtained in all populations within the Galician Farmer Sanitary Defence Associations (ADSG) in 2004. All animals ≥1 year of age were examined serologically by indirect ELISA. 1147 dairy herds (37,090 animals), 1464 beef herds (20,206 animals) and 141 mixed herds (2292 animals) were surveyed. True herd seroprevalence was estimated to be 80.6% (87.7% dairy, 76.7% beef and 78.4% mixed herds), true animal seroprevalence was estimated to be 23.2% (21.9% dairy, 25.1% beef and 24.9% animal to mixed herds), and within-herd seroprevalence was estimated to be 25.4% (23.6% dairy, 28.3% beef and 28.6% to mixed herds). Seropositivity was significantly associated with herd type (higher in dairies), herd size (increased when herd size increases), animal type (higher in beef) and age (lineal increase with the age). Results obtained in this study will be used for the development of a N. caninum control programme in the ADSG in Galicia.     

A strategy for control of bovine leukemia virus infection: test and corrective management

Test and corrective management was applied in one dairy herd (130 milking cows) to control bovine leukemia virus infection. It consisted of: raising uninfected calves in order to establish a pool of uninfected replacement heifers, preventing transmission of bovine leukemia virus through transfer of blood from animal to animal and closing the herd. Regular herd testing was combined with selected changes in herd management. These procedures have been followed since January 1979. Prevalence of antibodies (as determined by gel-immunodiffusion) has declined markedly since the program was implemented.     

Risk factors for the between-herd spread of Mycobacterium bovis in Canadian cattle and cervids between 1985 and 1994.

Microorganisms of the genus Mycobacterium cause tuberculosis in many animal species including humans. Generally, Mycobacterium bovis (M. bovis) infects cattle and cervids, but it has the potential to infect virtually all species of mammals. This study examined and analysed the data from the nine outbreaks of tuberculosis in Canadian cattle and cervids from 1985 to 1994. For the purposes of this study, a positive herd was one with at least one culture-positive animal. A reactor herd had at least one animal which was positive or suspicious on a mid-cervical, comparative cervical, or gross or histopathologic test for tuberculosis. Herd classification was either reactor/positive or negative. Data for the study were collected from the outbreak records in the Regional or District offices of Agriculture and Agri-Food Canada. Logistic regression was used to study spread of tuberculosis between herds. Two risk factors were identified: increasing herd size; and, the reason why a herd was investigated as part of the outbreak. This latter factor was interpreted as a surrogate measure for the nature of contact between the study herd and other potentially infected herds in the outbreak. Increasing herd size was associated with an increased risk of being positive for tuberculosis with herds of 16-35, 36-80, and >80 animals having odds ratios of 2.9, 5.8, and 9.3, respectively, when compared to a herd size of <16 animals (p < 0.001). When compared to perimeter testing (i.e. testing herds within a specified radius of an infected herd), all other reasons for investigation had higher odds ratios (p < 0.001). These odds ratios were 57.8 for traceout herds (i.e. herds which had purchased animal(s) from a reactor/positive herd), 31.8 for herds with pasture or fence-line contact with a reactor/positive herd, and 14.9 for traceback herds (i.e. herds which had been a source of animals for reactor/positive herd(s)).     

Bayesian analysis of animal movements related to factors at herd and between herd levels: Implications for disease spread modeling

A method to assess the influence of between herd distances, production types and herd sizes on patterns of between herd contacts is presented. It was applied on pig movement data from a central database of the Swedish Board of Agriculture. To determine the influence of these factors on the contact between holdings we used a Bayesian model and Markov chain Monte Carlo (MCMC) methods to estimate the posterior distribution of model parameters. The analysis showed that the contact pattern via animal movements is highly heterogeneous and influenced by all three factors, production type, herd size, and distance between holdings. Most production types showed a positive relationship between maximum capacity and the probability of both incoming and outgoing movements. In agreement with previous studies, holdings also differed in both the number of contacts as well as with what holding types contact occurred with. Also, the scale and shape of distance dependence in contact probability was shown to differ depending on the production types of holdings.To demonstrate how the methodology may be used for risk assessment, disease transmissions via animal movements were simulated with the model used for analysis of contacts, and parameterized by the analyzed posterior distribution. A Generalized Linear Model showed that herds with production types Sow pool center, Multiplying herd and Nucleus herd have higher risk of generating a large number of new infections. Multiplying herds are also expected to generate many long distance transmissions, while transmissions generated by Sow pool centers are confined to more local areas. We argue that the methodology presented may be a useful tool for improvement of risk assessment based on data found in central databases.     

Serologic progression studies using CF and ELISA for the detection of antibodies against Eperythrozoon suis infection of swine

Serological studies by means of a CF-Test and Elisa were undertaken for evaluation of antibody titers against Eperythrozoon suis infection in swine. The animals were partly splenectomized and underwent artificial infection. It could be shown that the splenectomized animals showed higher and longer lasting antibody titers than the non splenectomized swine. It is stated, that the above mentioned tests can be used in diagnosis on a herd basis but not on a single animal basis.     

Good animal welfare makes economic sense: potential of pig abattoir meat inspection as a welfare surveillance tool

ABSTRACT: During abattoir meat inspection pig carcasses are partially or fully condemned upon detection of disease that poses a risk to public health or welfare conditions that cause animal suffering e.g. fractures. This incurs direct financial losses to producers and processors. Other health and welfare-related conditions may not result in condemnation but can necessitate 'trimming' of the carcass e.g. bruising, and result in financial losses to the processor. Since animal health is a component of animal welfare these represent a clear link between suboptimal pig welfare and financial losses to the pig industry.Meat inspection data can be used to inform herd health programmes, thereby reducing the risk of injury and disease and improving production efficiency. Furthermore, meat inspection has the potential to contribute to surveillance of animal welfare. Such data could contribute to reduced losses to producers and processors through lower rates of carcass condemnations, trimming and downgrading in conjunction with higher pig welfare standards on farm. Currently meat inspection data are under-utilised in the EU, even as a means of informing herd health programmes. This includes the island of Ireland but particularly the Republic.This review describes the current situation with regard to meat inspection regulation, method, data capture and utilisation across the EU, with special reference to the island of Ireland. It also describes the financial losses arising from poor animal welfare (and health) on farms. This review seeks to contribute to efforts to evaluate the role of meat inspection as a surveillance tool for animal welfare on-farm, using pigs as a case example.     

Characterisation of the repeat breeding syndrome in Swedish dairy cattle

Repeat breeding (RB), defined as cows failure to conceive from 3 or more regularly spaced services in the absence of detectable abnormalities, is a costly problem for the dairy producer. To elucidate the occurrence of RB in Swedish dairy herds and to identify risk factors of the syndrome totally 57,616 dairy cows in 1,541 herds were investigated based on data from the official Swedish production-, AI- and disease-recording schemes. The characteristics of the RB syndrome were studied on both herd and individual cow level. The effects of risk factors on the herd frequency of RB were studied by logistic regression. A generalised linear mixed model with logit link, and accounting for herd-level variation by including a random effect of herd, was used to study the individual animal risk for RB. The total percentage of RB animals was 10.1% and the median proportion of RB animals in the herds studied was 7.5%. The proportion of RB cows in herds increased with decreased herd sizes with decreased average days from calving to first AI, with increased herd incidence of clinical mastitis, with decreased reproductive disorders, and increased other diseases treated by a veterinarian. On animal level, the risk factors were milk yield, lactation number, difficult calving or dystocia, season at first service, days in milk at first service and veterinary treatment for reproductive disorders before the first service. Cows being an RB animal in the previous lactation had a higher risk of becoming an RB animal also in the present lactation. In conclusion our results show that the repeat breeding syndrome is a multifactorial problem involving a number of extrinsic factors as well as intrinsic factors coupled to the individual animal.     

Congenital white muscle disease in a Belgian blue calf

In this case report about white muscle disease (WMD) in a Belgian Blue herd, the disease is described both as an individual and as a herd problem. Aetiology, diagnosis, and therapy of WMD are discussed. WMD is a disease of animals with muscle damage due to the presence of free radicals. Unsaturated fatty acids in the cell membrane are transformed into a radical form in a chain reaction: a fatty acid next to the fatty acid radical can be transformed into another free radical. In healthy animal the chain reaction is stopped by anti-oxidants such as vitamin E and glutathione peroxidase. WMD can occur when more free radicals are produced than the available anti-oxidants can deal with. The disease occurs in calves, lambs, and foals.     

Factors affecting the livestock herd size among smallholder households in Zambia

Structural changes in the economic and demographic landscapes in the developing countries create a host of opportunities for smallholder livestock producers to tap into the economic growth from which they have largely been excluded. However, small livestock herd sizes limit the opportunities available to farmers to commercialize and benefit from the growing demand for livestock and livestock products. Therefore, understanding what it takes to build and maintain the herd size is a critical step in addressing the problem of low market participation. The study used five cross-sectional nationally representative data sets to arrive at the following conclusions. While purchases are a primary source for the initial stock, births are the principal way of increasing the herd size. Livestock deaths as reflected by high mortality rates are the major outflow channel through which livestock leaves the herd, and reducing the mortality rates has a positive effect on the livestock population as evidenced within the cattle sub-sector. Thus, provision of adequate animal health services is key to addressing the high mortality rates which subsequently can lead to increased herd size. As births are the primary means of increasing the herd size, it is necessary to implement interventions that address the reproduction rates. The interventions include adequate feeding of livestock on high-quality feed and strategic feeding to address the dry season challenges. These interventions can facilitate the growth of the young livestock into mature breeding stock and thus increase the herd size.     

种植优良牧草提高圈窝子利用率试验

本试验针对目前海晏县旧圈窝子利用率低的现状，在废弃或闲置的圈窝子内种植多年生优良牧草紫花苜蓿和无芒雀麦，既可以增加优良牧草生产，提高畜牧业经济效益，增加农牧民的经济收入，又能减少天然草场上家畜的放牧时间，有利于草地生态的保护。     

Modelling BVD at herd level compared with individual animal level

We assess two closely related stochastic models of BVD in a beef herd for their utility. One is an individual (animal) based model and the other a herd based model.     

Bioeconomic evaluation of embryo transfer in beef production systems: I. Description of a biological model for steer production.

Concepts used to derive a deterministic model for evaluating embryo transfer for commercial steer production taking into consideration genetic merit for growth and mature size, herd feed supply, and recipient maternal environment are discussed. Genetic potential of an embryo is used to derive optimal growth rates that can be sustained by available herd feed per animal per day. Equations are provided for various measures of performance as functions of the feed, genotype of the embryo, and recipient maternal contribution. To assess the value of a particular line of embryos, interactions between genotype and nutrient environment are quantified, so that the benefits of embryos of high genetic merit are evaluated objectively. Product quality and weight are predicted from the model to provide a framework that will allow commercial beef producers to determine marketing strategies likely to result in optimal return.